From afdf0abe779f4b11712eb306ab2d4299820457b8 Mon Sep 17 00:00:00 2001
From: Kevin Wolf <kwolf@redhat.com>
Date: Tue, 27 Mar 2012 13:44:56 +0200
Subject: [PATCH] qcow2: Ignore reserved bits in check_refcounts

Also don't infer the cluster type directly from the L2 entries, but use
qcow2_get_cluster_type() to keep everything in a single place.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/qcow2-refcount.c | 102 ++++++++++++++++++++++-------------------
 1 file changed, 56 insertions(+), 46 deletions(-)

diff --git a/block/qcow2-refcount.c b/block/qcow2-refcount.c
index e0854dc85d..0112cc37b0 100644
--- a/block/qcow2-refcount.c
+++ b/block/qcow2-refcount.c
@@ -940,7 +940,7 @@ static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res,
     int check_copied)
 {
     BDRVQcowState *s = bs->opaque;
-    uint64_t *l2_table, offset;
+    uint64_t *l2_table, l2_entry;
     int i, l2_size, nb_csectors, refcount;
 
     /* Read L2 table from disk */
@@ -952,54 +952,64 @@ static int check_refcounts_l2(BlockDriverState *bs, BdrvCheckResult *res,
 
     /* Do the actual checks */
     for(i = 0; i < s->l2_size; i++) {
-        offset = be64_to_cpu(l2_table[i]);
-        if (offset != 0) {
-            if (offset & QCOW_OFLAG_COMPRESSED) {
-                /* Compressed clusters don't have QCOW_OFLAG_COPIED */
-                if (offset & QCOW_OFLAG_COPIED) {
-                    fprintf(stderr, "ERROR: cluster %" PRId64 ": "
-                        "copied flag must never be set for compressed "
-                        "clusters\n", offset >> s->cluster_bits);
-                    offset &= ~QCOW_OFLAG_COPIED;
-                    res->corruptions++;
+        l2_entry = be64_to_cpu(l2_table[i]);
+
+        switch (qcow2_get_cluster_type(l2_entry)) {
+        case QCOW2_CLUSTER_COMPRESSED:
+            /* Compressed clusters don't have QCOW_OFLAG_COPIED */
+            if (l2_entry & QCOW_OFLAG_COPIED) {
+                fprintf(stderr, "ERROR: cluster %" PRId64 ": "
+                    "copied flag must never be set for compressed "
+                    "clusters\n", l2_entry >> s->cluster_bits);
+                l2_entry &= ~QCOW_OFLAG_COPIED;
+                res->corruptions++;
+            }
+
+            /* Mark cluster as used */
+            nb_csectors = ((l2_entry >> s->csize_shift) &
+                           s->csize_mask) + 1;
+            l2_entry &= s->cluster_offset_mask;
+            inc_refcounts(bs, res, refcount_table, refcount_table_size,
+                l2_entry & ~511, nb_csectors * 512);
+            break;
+
+        case QCOW2_CLUSTER_NORMAL:
+        {
+            /* QCOW_OFLAG_COPIED must be set iff refcount == 1 */
+            uint64_t offset = l2_entry & L2E_OFFSET_MASK;
+
+            if (check_copied) {
+                refcount = get_refcount(bs, offset >> s->cluster_bits);
+                if (refcount < 0) {
+                    fprintf(stderr, "Can't get refcount for offset %"
+                        PRIx64 ": %s\n", l2_entry, strerror(-refcount));
+                    goto fail;
                 }
-
-                /* Mark cluster as used */
-                nb_csectors = ((offset >> s->csize_shift) &
-                               s->csize_mask) + 1;
-                offset &= s->cluster_offset_mask;
-                inc_refcounts(bs, res, refcount_table, refcount_table_size,
-                    offset & ~511, nb_csectors * 512);
-            } else {
-                /* QCOW_OFLAG_COPIED must be set iff refcount == 1 */
-                if (check_copied) {
-                    uint64_t entry = offset;
-                    offset &= ~QCOW_OFLAG_COPIED;
-                    refcount = get_refcount(bs, offset >> s->cluster_bits);
-                    if (refcount < 0) {
-                        fprintf(stderr, "Can't get refcount for offset %"
-                            PRIx64 ": %s\n", entry, strerror(-refcount));
-                        goto fail;
-                    }
-                    if ((refcount == 1) != ((entry & QCOW_OFLAG_COPIED) != 0)) {
-                        fprintf(stderr, "ERROR OFLAG_COPIED: offset=%"
-                            PRIx64 " refcount=%d\n", entry, refcount);
-                        res->corruptions++;
-                    }
-                }
-
-                /* Mark cluster as used */
-                offset &= ~QCOW_OFLAG_COPIED;
-                inc_refcounts(bs, res, refcount_table,refcount_table_size,
-                    offset, s->cluster_size);
-
-                /* Correct offsets are cluster aligned */
-                if (offset & (s->cluster_size - 1)) {
-                    fprintf(stderr, "ERROR offset=%" PRIx64 ": Cluster is not "
-                        "properly aligned; L2 entry corrupted.\n", offset);
+                if ((refcount == 1) != ((l2_entry & QCOW_OFLAG_COPIED) != 0)) {
+                    fprintf(stderr, "ERROR OFLAG_COPIED: offset=%"
+                        PRIx64 " refcount=%d\n", l2_entry, refcount);
                     res->corruptions++;
                 }
             }
+
+            /* Mark cluster as used */
+            inc_refcounts(bs, res, refcount_table,refcount_table_size,
+                offset, s->cluster_size);
+
+            /* Correct offsets are cluster aligned */
+            if (offset & (s->cluster_size - 1)) {
+                fprintf(stderr, "ERROR offset=%" PRIx64 ": Cluster is not "
+                    "properly aligned; L2 entry corrupted.\n", offset);
+                res->corruptions++;
+            }
+            break;
+        }
+
+        case QCOW2_CLUSTER_UNALLOCATED:
+            break;
+
+        default:
+            abort();
         }
     }
 
@@ -1070,7 +1080,7 @@ static int check_refcounts_l1(BlockDriverState *bs,
             }
 
             /* Mark L2 table as used */
-            l2_offset &= ~QCOW_OFLAG_COPIED;
+            l2_offset &= L1E_OFFSET_MASK;
             inc_refcounts(bs, res, refcount_table, refcount_table_size,
                 l2_offset, s->cluster_size);